The serine peptidase inhibitor N-ρ-tosyl-l-phenylalanine chloromethyl ketone (TPCK) affects the cell biology of Candida haemulonii species complex.

Candida haemulonii species complex (C. haemulonii, C. haemulonii var. vulnera and Candida duobushaemulonii) is composed by emerging and multidrug-resistant (MDR) yeasts. Candidiasis, the disease caused by these species, is difficult to treat and culminates in clinical failures and patient death. It is well-known that Candida peptidases play important roles in the fungus-host interactions, and hence these enzymes are promising targets for developing new antifungal drugs. Recently, serine-type peptidases were described in clinical isolates of C. haemulonii complex with the ability to cleave relevant key host proteins. Herein, the effects of serine peptidase inhibitors (SPIs) on the cell biology of this fungal complex were evaluated. Initially, eight distinct SPIs (phenylmethylsulfonyl fluoride - PMSF, 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride - AEBSF, N-α-tosyl-l-lysine chloromethyl ketone hydrochloride - TLCK, N-p-tosyl-l-phenylalanine chloromethyl ketone - TPCK, simeprevir, boceprevir, danoprevir and telaprevir) were tested on the fungal growth. TPCK showed the best efficacy in controlling cell proliferation, being selected for the following experiments. This SPI induced changes in the architecture of yeast cells, as observed by scanning electron microscopy, besides injuries at the plasma membrane and reduction in the ergosterol content. TPCK also diminished the ability of yeasts to adhere to abiotic (polystyrene and glass) and biotic (murine macrophages) surfaces in a typically concentration-dependent manner. In addition, the 24 h-treatment of the mature biofilm promoted a decrease in biomass, viability and extracellular matrix. Altogether, our results highlight that SPIs may be promising new therapeutic agents in the treatment of candidiasis caused by emergent, opportunistic and MDR species forming the C. haemulonii complex.

Novel antimony(iii) hydroxamic acid complexes as potential anti-leishmanial agents.

Reaction of benzohydroxamic acid (Bha), 2-pyridinehydroxamic acid (2-pyha), 2-amino-phenylhydroxamic acid (2-NH2-pha) and salicylhydroxamic acid (Sha) with SbCl3 in ethanol gave the corresponding novel hydroxamato Sb(iii) complexes, [Sb(Bha-1H)2Cl] 1, [SbCl2(2-pyha-1H)] 2, [Sb(2-NH2-pha-1H)(2-NH3-pha-1H)]Cl23 and [SbCl(Sha-1H)2] 4. In all cases the hydroxamic acids coordinate to the Sb centres in the typical bidentate hydroxamato (O,O') coordination mode, via the carbonyl oxygen and deprotonated hydroxyl group. Reaction of the histone deacetylase inhibitor (HDACi) suberoylanilidehydroxamic acid (SAHA) with Sb(OEt)3 gave the Sb(iii) hydroxamato/hydroximato complex, [Sb(SAHA-1H)(SAHA-2H)] 6. All test complexes significantly inhibited the promastigote proliferation of Leishmania amazonensis and L. chagasi and induced substantial changes in the general morphology of the parasites, including reduction in size and loss of flagellum, when compared to the untreated promastigotes. A dose-response approach using the test complexes showed a decreased in plasma membrane permeability and the mitochondrial dehydrogenase activities of the Leishmania species. [Sb(Bha-1H)2Cl] exhibited the best activity and was superior to the Sb HDACi complex 6. Though 1 exhibited noteworthy anti-leishmanial activity, the selectivity indexes determined suggest that [Sb(2-NH2-pha-1H)(2-NH3-pha-1H)]Cl23 is the test complex that merits further investigation as a potential anti-leishmanial agent.

Cruzipain: An Update on its Potential as Chemotherapy Target against the Human Pathogen Trypanosoma cruzi.

Chagas' disease is one of the most impactful and prevalent neglected tropical diseases in the Americas, specially affecting the poor and underdeveloped areas in Latin America. Aggravating this scenario, the medicines used in the current chemotherapy are old, toxic and present a low efficacy to treat the chronic stage of this disease. In addition, resistant strains of Trypanosoma cruzi, the etiological agent, are frequently reported. So, there is an imperative requirement for novel chemotherapeutic options to treat this debilitating disease. In this context, peptidases have emerged as potential targets and, consequently, proteolytic inhibitors have confirmed to be valuable drugs against several human pathologies. In this line of thinking, T. cruzi produces a major multifunctional cysteine peptidase, named cruzipain, which directly and/or indirectly orchestrates several physiological and pathological processes, which culminate in a successful parasitic infection. Taken together, these findings point out that cruzipain is one of the most important targets for driving a chemotherapy approach against the human pathogen T. cruzi. The present review summarizes some of the recent advances and failures in this area, with particular emphasis on recently published studies.

Calpains: potential targets for alternative chemotherapeutic intervention against human pathogenic trypanosomatids.

The treatment for both leishmaniasis and trypanosomiasis, which are severe human infections caused by trypanosomatids belonging to Leishmania and Trypanosoma genera, respectively, is extremely limited because of concerns of toxicity and efficacy with the available anti-protozoan drugs, as well as the emergence of drug resistance. Consequently, the urgency for the discovery of new trypanosomatid targets and novel bioactive compounds is particularly necessary. In this context, the investigation of changes in parasite gene expression between drug resistant/sensitive strains and in the up-regulation of virulence-related genes in infective forms has brought to the fore the involvement of calpain-like proteins in several crucial pathophysiological processes performed by trypanosomatids. These studies were encouraged by the publication of the complete genome sequences of three human pathogenic trypanosomatids, Trypanosoma brucei, Trypanosoma cruzi and Leishmania major, which allowed in silico analyses that in turn directed the identification of numerous genes with interesting chemotherapeutic characteristics, including a large family of calpain-related proteins, in which to date 23 genes were assigned as calpains in T. brucei, 40 in T. cruzi and 33 in L. braziliensis. In the present review, we intend to add to these biochemical/biological reports the investigations performed upon the inhibitory capability of calpain inhibitors against human pathogenic trypanosomatids.